“We must use time creatively - and forever realize that the time is always hope to do great things.”

Source: Natural Right and History (1953), p. 36

The third and fourth sentences are a paraphrase of a sentence by G. K. Chesterton: "I do not believe in a fate that falls on men however they act; but I do believe in a fate that falls on them unless they act." Generally Speaking, "On Holland' (1928).
1980s, First term of office (1981–1985), First Inaugural address (1981)
Context: It is time for us to realize that we're too great a nation to limit ourselves to small dreams. We're not, as some would have us believe, doomed to an inevitable decline. I do not believe in a fate that will fall on us no matter what we do. I do believe in a fate that will fall on us if we do nothing. So, with all the creative energy at our command, let us begin an era of national renewal. Let us renew our determination, our courage, and our strength. And let us renew our faith and our hope. We have every right to dream heroic dreams. Those who say that we're in a time when there are no heroes, they just don't know where to look.

The Tyranny of Hate: The Roots of Antisemitism : A Translation into English of Memsheleth Sadon (1992), p. 25

1960s, Letter from a Birmingham Jail (1963)
Context: I had also hoped that the white moderate would reject the myth concerning time in relation to the struggle for freedom. I have just received a letter from a white brother in Texas. He writes: "All Christians know that the colored people will receive equal rights eventually, but it is possible that you are in too great a religious hurry. It has taken Christianity almost two thousand years to accomplish what it has. The teachings of Christ take time to come to earth." Such an attitude stems from a tragic misconception of time, from the strangely irrational notion that there is something in the very flow of time that will inevitably cure all ills. Actually, time itself is neutral; it can be used either destructively or constructively. More and more I feel that the people of ill will have used time much more effectively than have the people of good will. We will have to repent in this generation not merely for the hateful words and actions of the bad people but for the appalling silence of the good people. Human progress never rolls in on wheels of inevitability; it comes through the tireless efforts of men willing to be co-workers with God, and without this hard work, time itself becomes an ally of the forces of social stagnation. We must use time creatively, in the knowledge that the time is always ripe to do right. Now is the time to make real the promise of democracy and transform our pending national elegy into a creative psalm of brotherhood. Now is the time to lift our national policy from the quicksand of racial injustice to the solid rock of human dignity.

Sakharov Prize for Freedom of Thought Acceptance Speech (2013)

Cork address (1885)

Source: Speak, Memory